The official said that "on at least one occasion the [Foreign Intelligence Surveillance Court]" ruled that some surveillance collected was "unreasonable under the Fourth Amendment." The official also stated that FISC, the court that reviews surveillance under FISA, found that the surveillance had "circumvented the spirit of the law" on "at least one occasion."

EFF says the Office of Information Policy and National Security Division, both within the Justice Department, have failed to process its FOIA requests for more information about these alleged violations. The San Francisco-based organization filed its suit against Justice on Thursday in the U.S. District Court for the District of Columbia.

The Justice Department declined to comment on the suit.

EFF argues that releasing this information on NSA's actions is critical because the surveillance provisions in the FAA sunset at the end of the year, and Congress will soon begin debate on whether to reauthorize the law.

"When law-breaking is allowed to remain secret, there's no accountability or way to monitor future abuses," Mark Rumold, an open-government legal fellow at EFF, said in a statement. "It's time for the government to come clean and tell us about the NSA's unconstitutional actions."